June 29, 2010 -- Adult obesity rates increased in 28 states in the past year, with the No. 1 ranking going to Mississippi, where 33.8% of adults are obese, according to a new report, "F as in Fat: How Obesity Threatens America's Future 2010."

Other major findings in the report:

38 states have adult obesity rates above 25%. (No state had an obesity rate above 20% in 1991.)

10 of the 11 states with the highest rates of obesity are in the South.

The number of states where obesity rates exceed 30% has doubled in the past year, from four to eight -- Alabama, Arkansas, Kentucky, Louisiana, Mississippi, Oklahoma, Tennessee, and West Virginia.

19.1% of people in Colorado are obese, the lowest rate of any state.

The number of adults who report they do not engage in any physical activity rose in 12 states in the past year.

Adult obesity rates for African-Americans and Latinos are higher than obesity rates for whites in at least 40 states and the District of Columbia.

Among adults who did not graduate from high school, 33.6% were obese, compared to 22% with college degrees.

12% of high school students are obese and 15.8% are overweight.

10 of the 11 states with the highest rates of diabetes are in the South, as are the 10 states with the highest rates of hypertension.

High rates of obesity are associated with lower incomes, race, ethnicity, and less education, according to the report from the Trust for America's Health (TFAH) and the Robert Wood Johnson Foundation.

"Obesity is one of the biggest public health challenges the country has ever faced, and troubling disparities exist based on race, ethnicity, region, and income," Jeffrey Levi, PhD, executive director of TFAH, says in a news release. "This report shows that the country has taken bold steps to address the obesity crisis in recent years, but the nation's response has yet to fully match the magnitude of the problem."

Levi, a professor of health policy at George Washington University School of Public Health and Health Services, says that "millions of Americans still face barriers -- like the high cost of healthy foods and lack of access to safe places to be physically active -- that make healthy choices challenging."

Among other key findings:

More than 12 million children and adolescents are obese. The percentage of kids engaging in vigorous physical activity daily ranges from a low of 17.6% in Utah to a high of 38.5% in North Carolina.

50% of people surveyed say more money should be invested in preventing childhood obesity.